Manufacture of a wiring loom

ABSTRACT

The invention relates to at method for manufacturing a wiring loom for use for example in a vehicle, comprising the following steps, a) on the assembly side ( 6 ) of an assembly support ( 1 ) is applied a base layer ( 5 ) which adheres at least temporarily to said assembly side and follows, at least partly, the course of the wiring loom during the manufacturing process; b) on the base layer ( 5 ) are fixed preferably a plurality of juxtaposed conductors in a substantially parallel arrangement c) finally, on the base layer is dusted or poured a coating layer ( 10 ) of a liquefied or molten material, which embeds said conductors, adheres to the base layer and, once poured or dusted, hardens or becomes globally more consistent.

[0001] So-called wiring boards are used in a conventional method ofproducing a cable harness, particularly for motor vehicles. The latercourse of the cable harness on a wiring board is predetermined. Theindividual wires are successively secured to the wiring board with theaid of mechanical fixing elements.

[0002] A cable harness is typically equipped with connecting elements,such as plugs or bushings. The individual wires are usually wound withthe aid of adhesive tape for ensuring that the individual wires willremain bundled. In many cases, this type of fixing or jacketing isinadequate. In these instances, the cable harness is inserted into aninjection mold and cast or foamed with a plastic material.

[0003] Clearly, this type of manufacturing method is very labor- andcost-intensive. Therefore, different alternative manufacturing methodshave been proposed; these have been used especially for smaller cableharnesses or flat cable harnesses. For example, DE 27 58 491 discloses amethod of producing a flat cable harness, in which a film is producedfrom a granulated, thermoplastic hot-melt plastic adhesive. In aninsertion apparatus, the individual wires of a flat cable harness arepositioned parallel to one another, and the hot-melt adhesive film islaid over the lines. Due to a slight pressure in a heating apparatus,the hot-melt adhesive is melted onto the lines.

[0004] DE 27 58 472 discloses a method of producing a flat cableharness, in which the individual wires, which are already provided withan insulation, are arranged between two layers of film, with the filmlayers being connected to one another through a high-frequency weldingmethod.

[0005] DE 37 40 593 C2 describes a method in which the cable harness ora wiring arrangement is integrated into a door frame. The door framecomprises a synthetic resin. The lines constituting the wiringarrangement are either laid in grooves of the synthetic-resin doorframe, embedded in the synthetic-resin material through ultrasonicwelding or etched onto the surface of the door frame.

[0006] It is the object of the invention to propose an alternativemethod of producing a cable harness, with which even cable harnesses ofa complex nature can be produced, and which is not only suited for aseparate cable harness production, but also for the construction of acable harness directly on a vehicle component. Furthermore, the methodis intended to be virtually completely automated.

[0007] This object is accomplished by a method having the features ofclaim 1. Accordingly, an essentially strip-shaped base layer, whichfollows the later course of the cable harness, at least in sections, isapplied to the assembly side of an assembly support. The base layeradheres, at least temporarily, to the assembly support. The base layeris preferably automatically put in place with the aid of a robot. Thewires are also laid on the base layer by a robot. It is conceivable thata laying head removes the individual wires from a wire magazine and laysthem, individually or several at a time, essentially parallel on thebase layer. From this point on, the term wires encompasses any type ofelectrical conductors, such as flat bands, metallically conductive ormetallically coated plastics, waveguides, metallic film conductors orthe like.

[0008] As the third method step, a cover layer comprising a liquid ormolten plastic material is sprayed, extruded, poured or brushed onto awire layer produced, for example, in the described manner, or agranulated or powdered plastic material is applied and subsequentlytreated in the manner of a sintering process with heat, ultrasound orthe like; in the process, the plastic material envelops the wires,adheres to the base layer and hardens, or generally converts to a moresolid consistency. Whenever the term liquid plastic material is used inthis description, it is also meant to encompass dual-component plastics.An example of such a plastic is polyurethane. The initial mixture ofthis type of plastic includes two components (olefin and cyanidecomponents) that react with one another as soon as they are mixedtogether. Assuming the simplest case, in which the base layer and thecover layer comprise the same material, the production of a single- ormulti-layer cable harness would merely necessitate a robot-guidedapplication head for the plastic mass and a laying apparatus for theindividual wires.

[0009] According to claim 2, the assembly support itself constitutes thevehicle component, for example a vehicle door. In such a case, the baselayer remains fixed to the vehicle component. This fixing can beattained solely through the adhesive properties of the cooperatingmaterials. To support the adhesive or material-to-material adherence,the vehicle component can have undercuts, such as interlacings ordepressions, which are filled with plastic material when the base layeris applied, thereby assuring an additional mechanical connection or aform fit between the base layer and the vehicle component.

[0010] Numerous automobile manufacturers are demanding an increasinglevel of completion from their suppliers. In view of these demands,suppliers are offering complete assemblies that essentially need only bemounted to the vehicle body in the manufacturing plant. An example ofsuch a component is a vehicle door or a tail gate. With the methodaccording to claim 2, it is conceivable to manufacture the cable harnessdirectly on the component in the supplier's plant.

[0011] The assembly support can, however, also be an assembly template,for example in the form of a table, a roller or a production band, withthe tabletop, the top of the production band or the circumferentialsurface of the roller respectively forming the assembly side. In such aprocedure, it is advisable for a separating layer to be applied to theassembly support, for example sprayed or brushed on, before the baselayer is applied; this separating layer permits the completed cableharness to be released from the assembly support. The respectively usedseparating means depends on the base layer/assembly support materialpairing, and, accordingly, varies from case to case.

[0012] The base layer is preferably produced as follows: First, a liquidplastic mass is sprayed, poured, extruded or brushed onto the assemblysupport; afterward, the plastic mass converts to a more solidconsistency, or at least hardens to a certain extent. Furthermore, thebase layer can be produced as described above for the cover layer—agranulated or powdered plastic material is applied, and the applicationof heat, ultrasound or the like subsequently effects a sort of sinteringof the plastic particles.

[0013] As mentioned above, the same material used for a cover layer canalso be used for the base layer, so the above description relating tothe material of the cover layer also applies here. For example, aquick-curing plastic can be used, that is, one that reaches its ultimateconsistency shortly after being applied. An example of this type ofplastic is a polyurea spray elastomer. The material is a relatively thininitial mixture of two components that react with one another(isocyanate and secondary or tertiary amine); they are brought intocontact with one another, or are mixed, in a mixer shortly before beingapplied to the assembly support. A plastic melt or the initial mixtureof a dual-component plastic can be used to produce the base layer. Anexample of this type of plastic is polyurethane. The base layer shouldtypically have a predetermined width. In the case of plastics that donot harden very quickly, an appropriate tool prevents the plastic meltor liquid initial mixture from flowing out. The plastic melt or theinitial mixture is, however, preferably thixotropically set, whichessentially prevents an applied plastic band from flowing out.

[0014] A prefabricated base band embodied in the manner of an adhesivetape or a film blank can also be used as the base layer. A base band ofthis type can either be affixed mechanically to the assembly support orpossibly affixed beneath a separating layer. In an especially preferredembodiment, further wires are laid on the first cover layer and afurther cover layer is applied. This cover layer can comprise the samematerial as the first cover layer. It can, however, consist of adifferent material, for example if the cover layer also serves as amechanical protection and, correspondingly, should have a greatermechanical resistance. It is also conceivable that the material of thefinal cover layer has a greater chemical resistance to the operatingmaterials of a motor vehicle than a lower cover layer or the base layer.The described method can be repeated multiple times for the constructionof multi-layer cable harnesses.

[0015] The wires can be laid on the base layer or the base band, on theone hand, and on a cover layer, on the other hand, in different ways. Inthe case of quick-curing plastics, it is advisable to lay the wires withthe aid of an adhesive. For this purpose, an adhesive is applied to thecorresponding, hardened or solidified layer in accordance with asuitable method, and the wires are laid on this adhesive layer. Thewires can also be self-adhesive; for example, they can be sprayed withan adhesive prior to being laid. With an appropriate selection of theplastic, the wires can be fixed to a base or cover layer throughhigh-frequency or ultrasonic welding. With thermoplastic plastics, therespective layer can be warmed, which at least partially sinks the wiresinto the warmed layer material and embeds them.

[0016] The connecting elements that are usually present on a cableharness can be mounted as follows: The electrical connecting elementsare preferably fixed, either permanently or detachably, to the assemblysupport before the base layer or base band is applied. The electricalconnecting elements are prepared such that their electrical contactelements, which are preferably embodied as insulation displacementcontacts, are freely accessible for producing the electrical-mechanicalconnection between the wire ends and the contact elements. Connectingelements having a clamshell housing, for example, can be used to assurethis accessibility. The one housing half, which supports the electricalcontact elements, is fixed in a recess or hole in the assembly support.

[0017] Another option is to fix the housing halves to the assemblysupport with the use of a vacuum. The wires of the first wire layer arelaid after the base layer has been applied to the assembly support; thecable ends of the wire ends are preferably pressed into the insulationdisplacement contacts of the connecting elements automatically, that is,by the laying apparatus itself.

[0018] Before the last cover layer is applied, the electrical connectingelements are completed by the positioning of the second housing half. Toseal the housing, it can be advisable to envelop the housing, at leastin the region of its separation joint, with plastic material, forexample when a closing cover layer is applied. The final cover layer isthen applied. If it is necessary to provide a longitudinal water seal,the transition region between the electrical connecting element and thecable harness can be enveloped with the material of the closing coverlayer. An alternative method is to omit the second housing half andprovide a hermetic seal of the connecting elements by introducing thecover-layer material into the half-shell-type housing of the connectingelement when the closing cover layer is applied.

[0019] The invention is described in detail below by way of embodimentsillustrated in the drawing, which shows in:

[0020]FIG. 1 a schematic, perspective view that outlines the steps ofthe method of the invention;

[0021]FIG. 2 a vehicle component having a cable harness that wasproduced in accordance with the invention;

[0022] FIGS. 3A-J sectional representations of different constructionvariations of cable harnesses that were produced in accordance with theinvention;

[0023]FIG. 4 a cutout of a cable harness having a formed-on fixingelement;

[0024]FIG. 5 a cutout, in perspective, of a flat cable harness having anintegrated electronic component; and

[0025]FIG. 6 a cross-sectional representation of a cable harness, inwhich a bridge connects two wires.

[0026]FIG. 1 illustrates a preferred variation of the method of theinvention, in which an original part of the motor vehicle, for example adoor frame, serves as the assembly support (1). A cable harness is to belaid directly on this door frame. Alternatively, the assembly supportcan also be an assembly template that includes a full-scalerepresentation of the three-dimensional course of the cable harness onthe original component. Hereinafter, however, reference is made to anassembly support that is the vehicle component itself.

[0027] Electrical connecting elements 3 of housing shells 2 that areopen to the top are first secured to the assembly support 1. For thispurpose, holes 4, into which the housing shells 2 are inserted, areprovided at predetermined positions. Insulation displacement contacts(not shown) are provided in the housing shells 2. Next, a base layer 5is applied to the assembly side 6 of the assembly support with the aidof an automatically-controlled application apparatus (not shown).

[0028] In FIG. 1, the base layer 5 is shown as being detached from theassembly support 1 for the sake of a clear overview. Numerous differentmaterials are available as the material for the base layer. The materialselection reflects, for example, the desired adhesion properties withrespect to the material of the assembly support 1, or depends on thetype of the intended, later connection between the individual wires ofthe cable harness and the base layer 5. The base layer can comprise theaforementioned polyurea spray elastomer, an adhesive, for example athermal adhesive, a thermoplastic plastic, a curable plastic, alight-curing plastic, a plastic that can be sintered, or the like. Anadhesive produced by Plasto, F-21304 Chenove Cedex, France, and marketedunder the brand name “K1 28” is preferably used as the material for thebase layer 5; this adhesive is a mixture of heat-meltable polymers andadditives. After being applied, this substance possesses a permanentstickiness, so the wires 7 forming the cable harness adhere securely toa base layer 5 comprising this material. The wires 7 can be insulated oruninsulated. The individual wires can follow, for example, only oneprimary branch, but can also branch off from it in the manner of a sidebranch. In the case of branch points in uninsulated wires, it isnecessary for at least the branch point 8 to be covered with aninsulation layer 9 before further wires that cross the branch points arelaid. Points on the cable harness that are heavily mechanically stressedare reinforced by additional cover-layer sections 9 a.

[0029] As the next step, a cover layer 10 is applied over the wires 7,likewise with the aid of an automatically-controlled applicationapparatus (not shown). The material of the cover layer is selected suchthat it connects to the material of the base layer 5. A material thatadditionally adheres to the wires 7 or their insulation is preferablyused. Next, the housing shells 2 of the electrical connecting elementsare completed with housing lids 11. The layer thickness of the baselayer 5 and the cover layer 10 varies depending on the respectiverequirements. It is also conceivable for the layers to have a foamyconsistency to save weight or influence the mechanical properties of thecable.

[0030] The material for the final cover layer is preferablyquick-curing, for example the aforementioned polyurea spray elastomer.This type of material seals the cable harness to the outside, and formsan essentially smooth surface that may be printed on or provided withidentifying features.

[0031] If the predetermined width of a base layer is insufficient forreceiving all of the necessary wires of the cable harness, a cableharness according to the invention can be constructed in multiplelayers. In this case, further wires are laid on a cover layer, and acover layer is applied over these wires. The new wires are not laiduntil the cover layer onto which the wires are to be laid has at leastpartially hardened or partially solidified. A further wire layer is thenlaid on the hardened cover layer in the above-described manner.

[0032]FIG. 2 shows the completed assembly support 1 with a cableharness. It is apparent that, in addition to the connecting elements 3,which comprise two housing halves, connecting elements 12, which aredisposed on a side branch 14 of the cable harness 13 that is notsupported by the assembly support 1, can be present on the cableharness. A connecting element 12 such as this is advisably mounted afterthe cable harness is complete. It can also be seen that built-incomponents such as a diagnosis connector 15 or an electronic componentcan be integrated into a cable harness of the invention.

[0033] FIGS. 3A-G show different cross-section shapes of a cable harnessof the invention. For the sake of simplification, the drawing showswires having identical cross sections. Wires having differentthicknesses and cross-section shapes can be present inside a cableharness, however. FIGS. 3A and 3B show a multi-layer cable harness thathas an approximately triangular cross section. This triangular shaperesults from the reduction in the widths of successive partial layers16, 16 a, 16 b, 16 c respectively encompassing a wire layer and a coverlayer. This is a requirement for cover layers that are to be producedthrough the application of a more or less fluid material. Amushroom-shaped fixing element 22 is formed onto the underside of thecable harness according to FIG. 3A. A similar fixing element 22 a isalso present in the cable-harness cutout of FIG. 4. These fixingelements 22, 22 a can be produced in that a molded hollow thatcorresponds to the mushroom-shaped fixing element is provided in theassembly support; the material of the base layer penetrates this hollowwhen it is applied. Another option is to dispose a prefabricated fixingelement in a receiving opening in the assembly support such that itprojects out of the assembly support with a fixing end and, when thebase layer is applied, is formed onto it.

[0034] A cable harness produced in the above-described manner can befixed to a vehicle component in that a double-sided adhesive film 23 isfixed to the outside, preferably in the region of the base layer, asshown in FIG. 3B. FIG. 3C shows a single-layer flat cable harness havinga total of five wires or lines 17. The surface of the cable harnessshown in FIGS. 3D and 3E has ribs 18, which extend parallel to oneanother in the longitudinal direction and can serve, for example, toreinforce the cable harness and protect against wear. In the cableharness according to FIG. 3F, a set of film lines 19 is laid on the baselayer 5 instead of a plurality of individual wires. In the cable harnessaccording to FIG. 3G, the wires 7 are embedded in a core 20 comprising afoam material. The foam core can be produced as follows: First, a coverlayer of a foam material is applied to the base layer 5, and the wires 7are in turn laid on the foam layer. If need be, a further foam layerthat covers the wires 7 can be applied. Finally, after the foam layerhas hardened, a final layer 21 that envelops the core 20 is applied. Inthe cable harnesses shown in FIGS. 3H and 3I, metal films 24 are used aswires or conductors. In 3H, the metal films have a rectangular crosssection. In the cable harness according to FIG. 3J, the metal filmslikewise have an essentially rectangular cross-section profile, buttheir edges are slightly rounded.

[0035] It is often necessary to integrate an electrical or electroniccomponent into the cable harness, as shown in FIG. 5, for example. Here,a cover layer 10 d is provided with a gap or an insulation window 24,which exposes the wires 7 b that are covered by the cover layer 10 d infront of and behind the window. The wires 7 b can be separated in theregion of the insulation window 24, and an electronic component 25, forexample, can be interposed. The insulation window is covered or sealedwith a cover-layer section (not shown) after the component 25 has beeninserted. This can be effected over the course of the layer constructionof a multi-layer cable harness. For adaptation to a relatively smallcomponent having a narrow connector grid pitch, it can be advisable tolay the wires with narrow spacing from one another in the region of theinsulation window 24. The base layer 5 and, accordingly, the coverlayers located above it, can be laterally narrowed, that is, they canhave a smaller width than the remainder of the cable harness. Inaddition to the aforementioned electronic components, bridges 26 canalso be produced in the described manner between the wires 7 of a cableharness, as shown in FIG. 6, for example.

1. A method of producing a cable harness, particularly for motorvehicles, comprising the following steps: a) an essentially strip-shapedbase layer (5) that follows the spatial course (6) of the cable harnessto be manufactured, at least in sections, is applied to the assemblyside of an assembly support (1), and at least temporarily adheres to theassembly side; b) a plurality of essentially parallel, adjacent wires(7) is fixed to the base layer (5); c) a cover layer (10) comprising aliquid or melted plastic material is sprayed, extruded, poured orbrushed onto the base layer, or a granulated or powdered plasticmaterial is applied and subsequently treated in the manner of asintering process with heat, ultrasound or the like, during whichprocess the plastic material envelops the wires (7) adheres to the baselayer and, following the application and, if applicable, following thesintering treatment, hardens or generally converts to a more solidconsistency.
 2. The method according to claim 1, characterized in thatthe assembly support (1) itself is the vehicle component, for example avehicle door, and the base layer (5) remains fixed thereto.
 3. Themethod according to claim 1, characterized in that an assembly templatein the form of a table, a roller or a production band is used as theassembly support (1), with the tabletop, the top of the projection [sic]band or the circumferential surface of the roller respectively formingthe assembly side.
 4. The method according to claim 3, characterized inthat a separating layer is disposed between the assembly support (1) andthe base layer (5), the separating layer being, for example, sprayed orbrushed onto the assembly side (6).
 5. The method according to one ofclaims 1 through 4, characterized in that the base layer (5) is producedin that a liquid or melted plastic material is sprayed, extruded, pouredor brushed onto the assembly support, or a granulated or powderedplastic material is applied and subsequently treated in the manner of asintering process with heat, ultrasound or the like, with the plasticmaterial hardening or generally converting to a more solid consistencyafter the application and possible sintering treatment.
 6. The methodaccording to claim 5, characterized in that the plastic material is aquick-curing plastic, for example a polyurea spray elastomer.
 7. Themethod according to claim 5, characterized in that a plastic melt or theinitial mixture of a dual-component plastic, for example polyurethane,is applied to the assembly support to produce the base layer (5).
 8. Themethod according to claim 7, characterized in that the plastic melt orthe initial mixture is thixotropically set.
 9. The method according toone of claims 1 through 4, characterized in that the base layer (5) is aprefabricated base band embodied in the manner of an adhesive tape or afilm blank.
 10. The method according to claim 9, characterized in thatthe base band is mechanically fixed to the assembly support (1).
 11. Themethod according to claim 9, characterized in that the base band isaffixed to the assembly support, possibly with the interposing of aseparating layer.
 12. The method according to one of claims 1 through11, characterized in that further wires are laid on the cover layer(10), and a further cover layer (10 a) is applied over the wires. 13.The method according to claim 12, characterized in that further wires(7) and further cover layers (10 b, 10 c) are assembled to form amulti-layer cable harness.
 14. The method according to one of claims 1through 13, characterized in that the wires are laid on the base layer(5) or a cover layer (10, 10 a, 10 b) with the aid of an adhesive. 15.The method according to one of claims 1 through 14, characterized inthat a thermoplastic plastic material is used as the material for thebase layer (5) or for the cover layer (10, 10 a, 10 b), and heat isapplied to this material to soften it, and the wires (7) to be laid areat least partially sunk into the softened material.
 16. The methodaccording to one of claims 1 through 15, characterized in that the wires(7) are laid shortly after a plastic material is sprayed, extruded orpoured to form a base layer (5) or a cover layer (10, 10 a, 10 b), thatis, the wires are laid before the plastic material has hardened.
 17. Themethod according to one of claims 1 through 16, characterized in that,before the base layer (5) is applied to the assembly support (1),electrical connecting elements (12) are permanently or detachably fixedto the assembly support, and the electrical contact elements, which arepreferably embodied as insulation displacement contacts, are freelyaccessible for the electrical-mechanical connection to the wire ends.18. The method according to claim 17, characterized in that theelectrical connecting elements (12) are closed with a housing lid (11)after a final cover layer (10) that serves as the top layer has beenapplied over the wires.
 19. The method according to claim 17,characterized in that, when the final cover layer is applied to thecable harness, the electrical connecting elements are at least partiallyfilled, cast or sprayed with the plastic material that forms the coverlayer.
 20. The method according to one of claims 1 through 19,characterized in that the cover layer is applied to the base layer (5)or a cover layer that is already on the base layer so as to form aninsulation window (24) that is not covered by the cover layer, with thewires (7 a) being freely accessible in this window for the connection ofan electronic component (25), a bridge (26) or the like.